Instrumentation for helioseismology. T.Appourchaux Institut d Astrophysique Spatiale, Orsay, France

Transcription

1 Instrumentation for helioseismology T.Appourchaux Institut d Astrophysique Spatiale, Orsay, France

2 Content The novelty with Plan-A Helioseismic instrumentation What can be done for Plan-A? Conclusion

3 Nishikawa et al (1986)

4 The novelty: stereoscopy Idea originates back from the 80 s for avoiding spatial gaps (full hemisphere instead of half hemisphere) Best way to probe the core (besides g-mode detection) What is the best instrumentation? Resolution, observable, angle separation (TBD) At least another instrument required (SDO, Solar orbiter)

5 Helioseismic instrumentation Ground based: Global Oscillation Network Group (GONG) Taiwan Oscillation Network (TON) Magneto-Optical filters (LOWL, ECHO) Space based: Luminosity Oscillations Imager (LOI / SOHO) Michelson Doppler Imager (MDI / SOHO) Solar Optical Telescope (SOT / Hinode) Helioseismic and Magnetic Imager (HMI / SDO) Polarimetric and Heliseismic Imager (SO / PHI)

6 Instruments Array Pixel (in arcsec) Pupil (in cm) Wavelength (in nm) Technique GONG 1k x 1k (Ni I) Velocity (tachometer) TON 1k x 1k K line Intensity ECHO 0.7k x 0.1k (K) Velocity (MOF) LOI 16 (total) Intensity MDI 1k x 1k (Ni I) Velocity (tachometer like) SOT / BFI 4k x 2k Ca II, R, G, B Intensity SOT / NFI 4k x 2k Mg IIb, Fe I HMI 4k x 4k (Fe I) PHI / HRT 2k x 2k (Fe I) PHI / FDT 2k x 2k (Fe I) Velocity (Lyot) Velocity (tachometer like) Velocity (Fabry-Perot) Velocity (Fabry-Perot)

7 Instrument Mass (kg) Telemetry (kbps) Power (Watt) Dimensions (cm 3 ) Built LOI x 9 x 9 ESA / SSD MDI x 40 x 24 (OP) Stanford / Lockheed SOT 46 (OP) Japan / USA HMI PHI x 53 x 24 (OP) 75 x 40 x 29 (OP) Stanford / Lockheed MPS / INTA / IAS

8 What can be done for Plan-A? Solar radial velocity: Better signal-to-noise ratio (300) Low-frequency modes Polarimetry as a «by-product» Wavelength stability demanding Large space experience Require a lot of glass (mass) Intensity: Lower signal-to-noise ratio (30) High-frequency modes No polarimetry Photometry not very demanding Space experience Light

9 Solar Radial Velocity for Plan-A? LYOT / Michelsons: Well space proven but heavy (>30 kg, <20kg?) LYOT only Space proven (besides the bubbles) but heavy? Several wavelength (if UBF like) Magneto-Optical Filters Not space provenbut Na cell aboard SOHO (GOLF) Various gases: Na, K, Ca, He Require magnets (2 of them, heavy?) No moving parts Fabry-Perot Space proven (but not for solar physics) Light if Lithium Niobate is used (solid etalon) Several wavelengths

10 Intensity for Plan-A? Various wavelength and various passbands All space proven Light Use of CCDs, photodiode or APS

11 What can be done for Plan-A? A strawman design: Entrance pupil of 10 cm dia (1 arcsec resolution) Detector: at least 4k x 4k (10 µm pitch) Full disk Observables: Velocity: various wavelengths Intensity: wide passbands Several instruments: 2 different wavelengths / heights for velocity 1 wavelength for intensity Mass / ressources: Total 25 kg for 1 instrument or 3 instruments? If 3 instruments: 10 kg for each wavelength (realistic?), 2 kg for intensity (well feasible)

12 Conclusion Ressources will drive the design (not new), especially mass Solar radial velocity preferred but intensity easier Do we want to do a better-than instrument? Stereoscopy: What is the best instrumentation? At least another required (SDO, Solar orbiter)

13 Comments on mission profile > 45 deg: 70 deg after 10 years of Scenario A_Ballistic 1: THANK YOU! Observation during cruise phase : YES! Circular orbit: BETTER!

14 Plan A vs Plan B Competition with an other mission in Japan? If no, Solar-C could also be appealing to solar physicists outside Japan If yes, Solar-C must be appealing to nonsolar physicists in Japan